TL;DR | Features | Backups | Failures | Usage | License

This shell script mimics the behavior of OSX's timemachine. It uses rsync to incrementally backup your data to a different directory or hard disk. All operations are incremental, atomic and automatically resumable.

By default the only rsync option used is --recursive. This is due to the fact that some remote NAS implementations do not support symlinks, changing owner, group or permissions (due to restrictive ACL's). If you want to use any other rsync arguments, you can simply append them.

Using POSIX.1-2008 argument syntax:

# Recursive, incremental and atomic backup
$ timemachine /source/dir /target/dir

# Append rsync options
$ timemachine /source/dir /target/dir -- --specials --progress
$ timemachine /source/dir /target/dir -- --specials --links --times --perms
$ timemachine /source/dir /target/dir -- --archive --progress

# Make the timemachine script be more verbose
$ timemachine -v /source/dir /target/dir
$ timemachine --verbose /source/dir /target/dir

# Make the timemachine script and rsync more verbose
$ timemachine -v /source/dir /target/dir -- --verbose
$ timemachine --verbose /source/dir /target/dir -- --verbose

Backups are always done incrementally using rsync's ability to hardlink to previous backup directories. You can nevertheless always see the full backup on the file system of any incrementally made backup without having to generate it. This will also be true when deleting any of the previously created backup directories. See the Backups section for how this is achieved via rsync.

Incremental Backups also mean that only the changes on your source, compared to what is already on the target have to be backed up. This will safe you time as well as disk space on the target disk.

When backing up, files are transmitted partially so in case a 2GB movie file backup is interrupted, the next run will pick up exactly where it left off at that file and will not start to copy it from scratch.

Not only is this script keeping partial files, but the whole backup run is also resumable. Whenever there is an unfinished backup and you start timemachine again, it will automatically resume it. It will resume any previously failed backup as long as it finally succeeds.

The whole backup procedure is atomic. Only if and when the backup procedure succeeds, it is also properly named and symlinked. Any non-successful backup directory is either waiting to be resumed or to be deleted.

The following directory structure will be created:

$ /bin/ls -lFgG /my/backup/folder
drwxr-xr-x 3 4096 Jan  6 18:43 2018-01-06__18-43-30/
drwxr-xr-x 3 4096 Jan  6 18:44 2018-01-06__18-44-23/
drwxr-xr-x 3 4096 Jan  6 18:50 2018-01-06__18-50-44/
drwxr-xr-x 3 4096 Jan  6 18:50 2018-01-06__18-50-52/
lrwxrwxrwx 1   20 Jan  6 18:50 current -> 2018-01-06__18-50-52/

current will always link to the latest created backup. All backups are incremental except the first created one. You can nevertheless safely remove all previous folders and the remaining folders will still have all of their content.

Backups are done incrementally, so least space is consumed. Due to rsync's ability, every folder will still contain all files, even though they are just incremental backups. This is archived via hardlinks.

$ du -hd1 .
497M    ./2018-01-06__18-43-30
24K     ./2018-01-06__18-44-23
24K     ./2018-01-06__18-50-44
24K     ./2018-01-06__18-50-52
497M    .

You can also safely delete the full backup folder without having to worry to loose any of your full backup data:

$ rm -rf ./2018-01-06__18-43-30
$ du -hd1 .
497M    ./2018-01-06__18-44-23
24K     ./2018-01-06__18-50-44
24K     ./2018-01-06__18-50-52
497M    .

rsync is magic :-)

In case the timemachine script aborts (self-triggered, disk unavailable or any other reason) you can simply run it again and it will automatically resume the last failed run.

There will be a directory .inprogress/ in your specified destination. This will hold all already transferred data and will be picked up during the next run.

$ timemachine -h

Usage: timemachine [-v] <source> <destination> -- [rsync opts]
       timemachine -V
       timemachine -h

This shell script mimics the behavior of OSX's timemachine.
It uses rsync to incrementally backup your data to a different directory.
All operations are incremental, atomic and automatically resumable.

By default the only rsync option used is --recursive.
This is due to the fact that some remote NAS implementations do not support
symlinks, changing owner, group or permissions (due to restrictive ACL's).
If you want to use any of those options you can simply append them.
See Example section for how to.

Required arguments:
  <source>        Source directory
  <destination>   Destination directory. Can also be a remote server

Options:
  -v, --verbose   Be verbose.

Misc Options:
  -V, --version   Print version information and exit
  -h, --help      Show this help screen

Examples:
  Simply backup one directory recursively
      timemachine /home/user /data
  Do the same, but be verbose
      timemachine -v /home/user /data
  Append rsync options and be verbose
      timemachine /home/user /data -- --links --times --perms --special
      timemachine --verbose /home/user /data -- --archive --progress --verbose
  Recommendation for cron run (no stdout, but stderr)
      timemachine /home/user /data -- -q
      timemachine /home/user -v /data -- --verbose > /var/log/timemachine.log

MIT License

Copyright (c) 2017 cytopia